The instillation of medicinal eye drops tends to be difficult and annoying for many individuals. Generally, a person tilts their head back and looks up. Simultaneously, the dropper bottle is elevated above and over the eye and the walls of the bottle are compressed, causing the drop to fall toward the eye.
Often, however, the drop misses the eye altogether and falls on the face, where it has no therapeutic value and may even be irritating to the skin. Or, several drops might be released if there is a momentary delay in the first drop and a second one is squeezed from the bottle, causing an overdose and waste of medicine.
The standard eye dropper tips that are currently being used, require that the bottle be held in a near vertically down position. This is necessary to make certain the drop falls from the end of the tip rather than adhere to the tip's external surface. The more vertically down the tip is held, the more likely the drop will fall from the end of the tip rather than adhere to and migrate along the external surface of the tip.
Once a drop does adhere to the external surface of the tip and refuses to fall, it attracts another drop because of molecular cohesive and adhesive forces. This is a result of surface tension. When the bottle and tip are held in a less vertically down orientation and in a more near horizontal position, some three or even four drops can be observed to adhere to each other and to the external surface of the tip rather than fall. The forces of cohesion and adhesion at times can be greater than the force of gravity acting upon the drop. When this happens, the drop(s) will continue to adhere to the surface of the dropper tip and migrate along its surface where a portion of the liquid will eventually fall from the base of the tip or even from the threaded portion of the bottle. One can readily see the amount of waste and the poor placement of the falling drop(s) that results. This may also cause a greater or a lesser dosage of medication to eventually fall into the eye, depending on the size of the drop.
There are several factors that often complicate the conventional way of instilling eye drops. First, it is difficult for some individuals, especially the elderly, to elevate their shoulder high enough to place the eye dropper in an ideal position above the eye. Secondly, limitation of motion of the hand or the wrist makes it difficult to turn the bottle in a substantially inverted position. Thirdly, some individuals, as they grow older, find that their hands and head are no longer steady, thus posing the problem of not being able to maintain proper alignment while the drops are being instilled. It is interesting that many patients, even without these limitations, confess that they are never sure where the drop will fall, even though they use drops on a regular, daily basis.
There are some persons who are unable to administer their own drops and either rely on a spouse or a caregiver to instill them. Often the caregiver finds it difficult to get the patient to open their eyes widely while the drops are being instilled. When the hand of the assistant comes in front of the eye, holding the bottle vertically down and obscuring the vision, there is a very strong protective reflex to close the eyelids. This makes it difficult to instill the drops with any accuracy and often the drop misses the eye and runs down the cheek. At that point one doesn't know if a drop or a portion of a drop did indeed get into the eye.
The vast majority of individuals administer their own drops and it is imperative to devise a better delivery system for the benefit of these individuals. It is important that the condition for which the drops are taken is adequately treated and that waste is kept to an absolute minimum.
Billions of dollars are spent annually just to treat glaucoma. It is obvious that a significant amount of these dollars are wasted because of the present delivery system for these medications. Presently, insurance companies, health maintenance organizations, governmental programs and especially patients themselves are concerned about the cost of treating various medical conditions. It is essential that the delivery system for ocular medications be reexamined and improved.
It has been observed that a commonly used anti-glaucoma medication in a 2.5 ml (milliliters) bottle on the market today, will release about 105 drops when the bottle is held in a vertically down position. However, when the bottle and tip is held down approximately 10 to 15 degrees, which is frequently the angle that individuals hold the dropper, only about 75 drops can be made to fall from the end of the dropper tip. The rest of the liquid tends to adhere to the outer surface of the tip and roll down the dropper tip toward its base and onto the bottle itself. It is obvious that there is considerable waste and a lack of accuracy in the instillation of drops into an eye with the present delivery system.
Once a drop adheres to the external surface of the dropper tip rather than fall, further drops released from the tip will continue to adhere to each other and to the surface of the tip. These drops will migrate along the external surface of the tip. There will always be a portion of this liquid that does not fall and when the cap is placed on the bottle, this liquid adheres to and dries out on the inside of the cap and on the outside of the bottle. This accounts for the dried-out material that is often found on both the internal threads of the cap and the external threads of the bottle after the bottle has been used up.
Not only is an improved dropper tip needed, but an improved dropper bottle to complement such a tip is mandatory. Most dropper bottles made and used today, must also be held in a near vertically down position to get the last third of the liquid in the bottle to flow to the tip where it can be expressed in drop form.
(A dropper bottle to complement the present invention has been designed that makes drop instillation more accurate, consistent and simultaneously permits the patient to hold the dropper bottle and dropper tip in a near horizontal orientation when the drop is released into an eye. A patent for such a newly designed bottle has been filed with the U.S. Patent and Trademark Office; Titled, "Precision Release Eye Dropper Bottle"; Inventor, James Hagele; PTO Application No., 09/272,066; Filing Date, Mar. 16, 1999; Preliminary Class, 604.)